Design and numerical investigation of Cs2SnI6 vacancy-ordered double perovskite solar cell

Perovskite solar cells (PSCs) represent an emerging technology in solar photovoltaics due to their outstanding optical and electrical characteristics. The urgency of lead-free solar materials has increased due to the environmental concerns. In light of these considerations, Cs₂SnI₆, a high-performance tin-based double perovskite, holds the potential to be a key absorber material in promoting the cell efficiency. In this paper, a device design of lead-free Cs₂SnI₆-based PSC is proposed based on an n-i-p planar structure. Through a comprehensive analysis by simulation using SCAPS-1D, the impacts of electron transport layer materials (SnO₂, TiO₂, CdS, GO, MZO) and hole transport layer materials (MoO₃, Cu₂O, CuI, Spiro-OMeTAD) with varying thicknesses as well as the donor density, acceptor density and the absorber thickness have been examined. Additionally, an examination is conducted on the performance metrics of PSCs, encompassing V_oc, J_sc, FF, and PCE, while taking into consideration the influences of temperature, R_series, and R_shunt. The results show that the optimized FTO/SnO₂/Cs₂SnI₆/MoO₃/Au device presents the highest PCE of 22.60 % at 300 K temperature, together with a visible quantum efficiency of 99.49 %. The appropriate thicknesses of the ETL, HTL, and absorber layer for achieving the optimal performances are 50 nm, 200 nm, and 450 nm, respectively. Also, the donor density and acceptor density for the best efficiency are both at 10¹⁸ cm⁻³. The values of R_series, and R_shunt are 2 Ω cm² and 6000 Ω cm², respectively. This investigation demonstrates that the proposed vacancy-ordered double perovskite Cs₂SnI₆ solar cell is promising for photovoltaic devices due to the highlighted characteristics and optical parameters.